Process-Microstructure Relationships in the Twin Wire Arc Zinc Process

A design of experiments approach was used to characterize process-microstructure relationships in the twin wire arc process using zinc feed stock. Specifically, the effect of arc current, primary atomizing gas pressure, secondary atomizing gas pressure, and standoff distance on deposition efficiency, spray pattern shape, atomization behavior, coating porosity, and coating surface roughness were investigated. All work was conducted using a Praxair 8835 torch spraying O2Z zinc feed stock. It was found that primary and secondary atomizing gas pressure significantly affected spray pattern shape, atomization behavior, coating porosity and coating surface roughness. Arc current significantly affected spray pattern shape. Standoff distance significantly affected deposition efficiency, spray pattern shape, and surface roughness.  Discussion will focus on using the relationships identified through this experiment to tune the wire arc process.

Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.